1. Field of the Invention
The invention relates to a thin film transistor (TFT) and a pixel structure. More particularly, the invention relates to a TFT in which a channel length can be adjusted based on different requirements and a pixel structure having the TFT.
2. Description of Related Art
In recent years, the progress toward the semiconductor manufacturing technology leads to fast and easy fabrication of TFTs. The TFTs can be extensively applied to computer chips, cellular phone chips, thin film transistor liquid crystal displays (TFT LCDs), and so forth. The TFT in a TFT LCD can act as a charging switch or a discharging switch for controlling pixels to display images, for instance.
According to the related art, a source and a drain of the TFT are formed by patterning the same conductive layer. The horizontal distance from the source to the drain is at least 3 μm, so as to ensure that the source and the drain are separated from each other. That is to say, when one conductive material layer is patterned to form the source and the drain through performing a photolithography and etching process, the horizontal distance from the source to the drain cannot be further shortened. Hence, the channel length and the area of the TFT cannot be further reduced.
Nonetheless, owing to the increasing requirements for device characteristics of various electronic products, the TFTs need to be characterized by great current output. The restricted channel length is unfavorable to the increase in the current output, which restrains the development of the TFTs.